Hi guys. I hope someone can help me. I'm at my wit's end! I've read a couple of things online about this problem but can't seem to find a solution.

I've got an unlocked T-Mobile 8100 on AT&T in which I'm trying to use a SanDisk 8GB Micro SD card.

My problem is that while the card is recognized by the BB itself, it's not recognized at all by my PC. It's not recognized in Roxio Media Manager (all it can access is the Device Memory) or in Windows as a Mass Storage Device, even though this is enabled. Windows just doesn't do anything after the BB has been first attached, recognized and installed automatically. Nothing at all related to the BB is listed in Administrative Tools/Computer Management/Disk Management. There are no other devices attached taking up lower drive letters (there's just the C: and DVD drive).

I've tried a bunch of other things to get it to work, with no luck:

I have tried different versions of the Desktop Manager, including the latest version. I've tried cleanly uninstalling and reinstalling the Desktop Manager.

I've tried two different micro SD cards.

I've tried the latest official OS (formatted by the phone to 4GB, as per the OS's limitations), plus the betas of 4.5.0.18 and 4.5.0.37 (both formatted by the phone to maximum capacity).

I have tried formatted the card using my PC.

I have made sure I have these settings:
Media Card Support: ON
Encryption: none
Mass Storage Mode Support: ON
Auto Enable Mass Storage Mode When Connected: YES

Yeah, I read about the drive letter problem, which is why I mentioned that the BB is not listed at all in Administrative Tools/Computer Management/Disk Management when attached (and also that there are no other external devices attached taking up lower drive letters), even though the Desktop Manager can recognize it.

I've read a bit about people having this problem, but it seems that after trying a few suggestions that sometimes solve it (like the disk management issue), there's not much other stuff to try.

Not sure exactly what you mean by 'USB problem.' I did try a different USB cable and another computer. Is there something I'm missing?

Cheers for the suggestion, prym3. Unfortunately, this doesn't help. Neither the PC nor the BB respond when I attach the BB in 'prompt' mode. It's the same thing as when I had it set to Auto Enable.
The only time I ever get a reaction out of the BB when it's attached to my PC is when the Desktop Manager's open and detects it.
Can anyone else help?

Thanks rachamphetamine. I do have a card reader, and can add files using it, but I add and delete files every second day, and having to bust open the phone, remove the battery THEN the micro SD card (and back again) every time I want to edit my media seems a whole bunch of trouble, so anything I can do to get my BB w/ media card acting like a proper removable drive would be fantastic.

I have the exact same problem (Pearl 8100 with Sandisk 8GB microSD card). Oddly enough, though, my Mac can read the memory card just fine; it's only my Windows XP PC that doesn't seem to be able to read the memory card. I've formatted it as 4GB using the Pearl, and no luck; I've formatted it as 8GB in another phone and then put it in the Pearl, and again no luck (although the Pearl itself and my Mac can read the media card just fine with both variations in formatting capacity). I'm going to try it with a Windows Vista computer tomorrow, to see if perhaps it's an XP thing or simply a Windows thing in general. I'll let you know how that goes.

I'm assuming you mean that your Mac can read the memory card while it's inside the Pearl (in mass storage mode)? I just quickly tried my phone with my friend's Mac with no luck. Do you have the desktop manager installed on the Mac? Is that even necessary when you're running the memory card in mass storage mode?

Yeah, please let me know how you go with Vista. Man, I'd like to know the solution to this. Keep me posted if you have any breakthroughs and I promise to do the same.